Previous studies on carbon monoxide have shown that both physiologic and psychophysiologic effects occur consequent to exposure to even low levels of this contaminant of our environment. Suggestive information that ozone also has the potentialities of producing similar complex responses in man forms the basis of this proposed investigation. It is proposed to expose subjects to increasing levels of ambient ozone and at different levels of ventilation (induced by different levels of exercise) resulting in increased dosages of ozone for similar time units. The resultant functional changes being measured (physiological and psychophysiological) will be quantified in relation to the dosage of ozone and used to empirically derive a dose response nomogram (as was done of carbon monoxide). Ultimately it is hoped to more clearly delineate the physiological responses and adaptions of man to ozone. On the practical side, the data and evaluations of the processes involved in the responses to this substance may lead to more precise delineation of air quality standards and threshold limit values.